Cylindrocarpen Update

12 November, 2006

Corbans Viticulture in association with the Lincoln University research program in association with is investigating ways to control black foot disease. The research program will focus on nursery plants but the information gained from the trials will also provide clues for managing the disease in mature vineyards. This program is being conducted in two stages over three years

Stage One

In early 2005, black foot resistance was tested for the rootstock varieties most commonly used in New Zealand.

Fourteen rootstock varieties were first tested by growing rooted plants for three months in infested potting mix, in a Lincoln University greenhouse, and then assessing incidence of infection. Later the same year, six of these varieties were planted out into infested field soil at Lincoln University to validate the greenhouse results.

In late 2005, a number of chemical, physical and biological treatments that had seemed promising in overseas trials were also set up using field trials at Corbans Viticulture in Auckland and also in Marlborough. The three fungicides, Captan, Switch (cyprodinil + fludioxinil) and Carbendazim + flusilazole, were suspended in carnauba wax (as recommended by the Stellenbosch University researchers). The biological treatment was an aqueous solution of Tricho-Flow™ (Agrimm® Technologies Ltd). The callused cuttings of varieties 101-14 and 5C were soaked for 30 minutes in the designated treatments and then grown in infested soil for seven months. After lifting, a hot water treatment was applied to a further set of infected plants, to determine whether they could be ‘cured’ of infections. All of these plants were recently assessed for presence of the black foot pathogens (Cylindrocarpon species). Results are currently being analysed.

Stage 2

In late 2006, a Lincoln University greenhouse trial determined the ability of three mycorrhizal fungi (originally isolated from grapevines) to colonise the six most commonly used rootstock varieties. A second greenhouse trial has tested the ability of the two best mycorrhizal colonisers to protect grapevines against a mixture of the three Cylindrocarpon species known to be common in New Zealand vineyard soils. This trial is currently being assessed and then the activity of the best mycorrhizae will be confirmed in the field.

In summer 2006/07 soil treatments that may eliminate the pathogen from black foot infested soil are also being tested. The products to be tested comprise two chemical fumigants, an active compost and a Wormtech™ product, as well as the best of the mycorrhizal treatments. The trials will be run in the same sites previously used at Corbans Viticulture in Auckland and also in Marlborough. At Lincoln University, three rotation crop species will be also planted in the same soil as the previous trial, to determine whether rotation with a break crop can reduce levels of the soil-borne pathogen. The same varieties, 101-14 and 5C, will be used in all trial sites and the plants assessed for disease in winter 2007.

For more information please contact:

Dr Anna Graham at Corbans Viticulture: anna@corbansviticulture.co.nz

Dr Marlene Jaspers at Lincoln University: jaspersm@lincoln.ac.nz

Acknowledgement: To Dr Marlene Jaspers and Carolyn Beach, Lincoln University